Adam Greenberg's career slash line is .000/1.000/.000. On July 9, 2005, Greenberg made his debut with the Chicago Cubs when he entered a game against the Marlins as a pinch-hitter in the ninth inning. His major league debut ended abruptly, though, when Valerio de los Santos's first pitch, a 92-mph fastball, hit Greenberg on the side of the head.

Greenberg would struggle for years afterward with post-concussion syndrome, bouncing around the minors and eventually spending several seasons in independent leagues. Most recently, he joined Team Israel for its World Baseball Classic qualifiers. Today, however, Greenberg will risk his perfect career OBP in one at bat for the FloridaMiami Marlins.

The Marlins signed the 31-year-old lefty to a one-day contract, and he will get a chance to face baseball's reigning best comeback story, R.A. Dickey. Greenberg's return will be the culmination of a social media campaign called "One At Bat," started by filmaker and Cubs fan Matt Liston, who's video about the One At Bat campaign can be seen above.

There's a risk of one comeback story ironically screwing up another here, though, as it's possible Greenberg could cost Dickey his 20th win (and consequently the Cy Young), or Greenberg could look hopelessly overmatched after not seeing too many 80-mph knuckleballs in the indy leagues. Or Dickey could walk Greenberg, depriving him still of one official at bat. (Let's not talk about the fact that Dickey has also hit nine batters this year.)